Abstract:

：Guyang area is located in the northern margin of the North China Craton, and Neopaleozoic granites are widespread there. In these granitic intrusions, granodiorite occurs as late intrusive veins, and diorite enclaves can be found in the granodioritic veins. For these three kinds of rocks, major and trace elements are measured to constrain their geochemical characteristics, while zircons are measured by SHRIMP to provide U-Pb ages. All these samples are calc-alkaline series, and enriched in LILE and LREEs, and show a mild fractionated REE. On a primitive-mantle normalized spidergram, these rocks show distinctly negative Nb, Ta, Ti anomalies and positive Rb, Th, K anomalies. U-Pb dating of zircon yielded crystallization ages of 330.8Ma, 324.7Ma, and 329.2Ma for the granite, the granodiorite and the diorite, respectively, which belong to the early carboniferous.The early Carboniferous magmatic rocks in northern margin of North China Craton should be associated to the subducting of Paleo-Asian Ocean to the North China plate, since this occurred before the convergence of the Siberia Craton and the North China Craton. Granites should be generated from remelting of continental crust, and granodiorite probably produced by mixing granitic magma and dioritic magma.

Key words: North Guyang, SHRIMP Zircon U-Pb dating, Early Carboniferous, magma mixing